docs: def point_at(self, horizontal_distance, vertical_increment, azimuth):
          """
          Compute the point with given horizontal, vertical distances
          and azimuth from this point.
  
          :param horizontal_distance:
              Horizontal distance, in km.
          :type horizontal_distance:
              float
          :param vertical_increment:
              Vertical increment, in km. When positive, the new point
              has a greater depth. When negative, the new point
              has a smaller depth.
          :type vertical_increment:
              float
          :type azimuth:
              Azimuth, in decimal degrees.
          :type azimuth:
              float
          :returns:
              The point at the given distances.
          :rtype:
              Instance of :class:`Point`
          """
          lon, lat = geodetic.point_at(self.longitude, self.latitude,
                                       azimuth, horizontal_distance)
          return Point(lon, lat, self.depth + vertical_increment)